The baboon as a model for immunological studies of schistosomiasis mansoni will be further studied with emphasis on defining conditions of infection with Schistosoma mansoni leading to the development of immunity. The role of murine-like alpha 2-macroglobulin antigenic determinants on the parasite's surface will be examined in the contexts of evasion of host immune responses and molecular mimicry. Immunogenicity of these antigenic determinants in baboons and the extent of mimicry of host protein are of particular interest.